The present disclosure relates generally to automatic hand brakes and more specifically to a control system for automatic release of hand brakes.
Hand or parking brakes on rail vehicles generally include a chain connected to the vehicle brakes and wound around a wheel. The brakes are applied by rotating the wheel and tensioning the chain. The hand brake includes a trigger or lever which, when activated, automatically releases the tension on the chain and releases the parking hand brake.
Two cylinders may be provided on the hand brake to apply the brakes by turning the wheel to tension the chain and a second cylinder to release the brakes by interacting with the release trigger or lever. A pneumatic system to control the two cylinders manually is illustrated in U.S. Pat. No. 6,394,559, for example. The use of parallel manually actuated valves and electro-pneumatic valves is described in U.S. Pat. No. 7,014,275. The actuation of the electro-pneumatic valves as discussed herein may be by an electrically controlled pneumatic (ECP) brake network and through the cars control unit (CCU). The overall control system is described, for example, in U.S. Pat. No. 7,073,753.
Remote control of the hand brake by hand-held terminal is described in U.S. Pat. No. 6,175,784.
The present hand brake control system for a rail vehicle hand brake having a release trigger includes a cylinder for activating the release trigger of the hand brake and a source of pressure. A first valve includes first, second, and third ports, and selectively connects either the source of pressure to the cylinder through the first and third ports of the first valve or the cylinder to exhaust through the second and third ports of the first valve. A second valve includes first, second, and third ports, and selectively connects either the source of pressure or exhaust to the second port of the first valve through the third port of the second valve. The first valve may be a manually operated valve and the second valve may be an electro-pneumatic valve.
The first valve is a manually operated valve having a stable position connecting the second port of the first valve to the third port of the first valve and a manually operated position connecting the first port of the first valve to the third port of the first valve. The first valve has a manually operated rocker mechanism.
Linkage may be connected to the first valve and extends to at least two locations about the vehicle for manual operation of the first valve without mounting the vehicle.
The second valve has a stable position connecting exhaust to the second port of the first valve and an activated position connecting the source of pressure to the second port of the first valve.
The source of pressure may be a reservoir on the vehicle or a source of pressure off the vehicle connected by a tap. A check valve between the source of pressure and the first and second valves pre-charges the connection to the first and second valves.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.